The zebrafish, Danio rerio, has become widely accepted as a model for human disease. Small molecule screens have been performed to identify both modifiers of normal cardiovascular processes and modifiers of cardiovascular disease. High-throughput systems under development aim to measure heart rate but do not address other critical parameters of cardiovascular function such as blood velocity and distribution. We propose to develop a high-throughput system that would simultaneously: 1) measure heart rate; 2) generate a flow map of the major blood vessels; and 3) measure blood velocity in those vessels. The microscope-based system will utilize spectral domain optical coherence tomography with Doppler to generate, within a matter of seconds, a three dimensional structural image of zebrafish embryos and larvae and measure blood flow. In Phase I we will develop a breadboard system that will enable collection of images from both the dorsal and ventral views of the animals. Images of the vasculature both of the brain and of the tail will be collected. In the breadboard system the animals will be located and the scan angle will be adjusted manually. In Phase II a complete, automated screening system will be developed that includes: 1) software algorithms to rapidly locate the animals for imaging and adjust the scan angle along their axial length; 2) automated image collection; and 3) automated image processing. Phase II testing will include a pilot compound screen to identify modifiers of cardiac output. [unreadable] [unreadable] This research will develop technologies that will enable the use of zebrafish models of human disease in high-throughput screens for active pharmaceutical compounds. In particular, such screens are expected to accelerate discovery of new pharmaceuticals to treat cardiovascular diseases. [unreadable] [unreadable] [unreadable]